JP6054293B2 - Attachment mechanism for stent release - Google Patents

Description

  The present disclosure relates generally to medical devices and procedures, and more particularly to methods and systems for deploying stents within the vasculature.

  Prosthetic devices for implantation in living blood vessels or other similar organs are generally well known in the medical arts. For example, prosthetic grafts formed of biocompatible materials (eg, Dacron or expanded polytetrafluoroethylene (ePTFE) tubing) have been used to replace or bypass damaged or occluded natural blood vessels. It was.

  The graft tube material supported by the frame is known as a stent-graft or endoluminal graft. In general, the use of stents and stent-grafts for the treatment or separation (intraluminal repair or elimination) of vascular aneurysms and vascular walls thinned or thickened by disease is well known.

  Many stents and stent-grafts are “self-expanding”, i.e., inserted into the vasculature in a compressed or contracted state and allowed to expand when the restraint is removed. Self-expanding stents and stent-grafts typically use wires or tubes (eg, bent or cut) configured to provide a radially outward force and are made of stainless steel or nitinol ( Use a suitable elastic material such as nickel-titanium. Nitinol can also use shape memory properties.

  Self-expanding stents or self-expanding stent-grafts are typically configured in a tubular shape and sized to have a diameter slightly larger than the diameter of the blood vessel for which the stent or stent-graft is intended to be used. It is done. In general, rather than inserting stents and stent-grafts in a traumatic and invasive manner using open surgery, stents or stent-grafts are usually delivered by a less invasive intraluminal delivery, That is, at a convenient (and less traumatic) entry point, the site where the prosthesis is deployed through the skin or through continuous dilation to access the lumen or vasculature Deployed by delivering a contracted stent or stent-graft within the delivery system through the lumen.

  Intraluminal deployment in one example is a delivery catheter, coaxial inner tube (sometimes called inner tube (plunger)) and outer tube (sometimes called sheath) arranged for relative axial movement. Performed) using a delivery catheter. The stent or stent-graft is deflated and placed in the distal end of the sheath in front of the inner tube.

  The catheter is then directed and typically delivered through a blood vessel (eg, a lumen) so that the end of the catheter containing the stent or stent-graft is near the intended treatment site. Placed in. The inner tube is then held stationary while the delivery catheter sheath is retracted. The inner tube prevents the stent-graft from reversing when the sheath is retracted.

  As the sheath is retracted, the stent or stent-graft is gradually exposed from its distal end to its proximal end. Because the exposed portion of the stent or stent-graft expands radially, at least a portion of the expansion portion is in surface contact that substantially matches a portion of the interior of the vessel wall.

  During deployment, the distal end of the stent or stent-graft is the end closest to the heart via the blood flow pathway, while the proximal end of the stent or stent-graft is the end furthest from the heart . Further, the distal end of the catheter is typically identified as the end furthest from the operator (handle), while the proximal end of the catheter is the end closest to the operator (handle).

  For clarity of discussion, as used herein, the distal end of the catheter is the end furthest from the operator (the end furthest from the handle), while the distal end of the stent-graft The end is also the end furthest from the operator (the end furthest from the handle or the handle itself), i.e. the distal end of the catheter and the distal end of the stent-graft are the farthest from the handle, On the other hand, the proximal end of the catheter and the proximal end of the stent-graft are the ends closest to the handle. However, depending on the access location, those skilled in the art will appreciate that the distal and proximal end descriptors for the description of the stent-graft and delivery system may be consistent or vice versa in actual use. Will understand.

  Some self-expanding stents and stent-graft deployment systems each expose a stent or stent-graft increment at the distal end of the stent deployment (flare out or mushroom) as the sheath is pulled back Configured as follows. The distal end of the stent-graft is typically designed to expand during deployment to secure and seal the stent to the vessel wall. In some cases, the proximal end of the stent may pierce an attachment mechanism that couples the stent to the delivery system. Thus, complete release of the stent is prevented.

  The concepts presented herein relate to an attachment mechanism provided within a delivery system for releasing a stent from the delivery system.

  In one aspect, the delivery system is used to deploy a stent percutaneously. The system has an inner shaft assembly, and the attachment mechanism is coupled to the inner shaft assembly and configured to selectively engage the stent. The delivery sheath capsule is slidably provided over the inner shaft assembly and is configured to compressively receive the stent engaged with the attachment mechanism. The attachment mechanism is configured to pivot relative to the inner shaft assembly when the delivery sheath capsule is retracted to release the stent from the delivery system.

  In another aspect, an attachment mechanism for use in a delivery system comprising an inner shaft assembly and a delivery sheath capsule is disclosed. The attachment mechanism includes a casing coupled to the inner shaft assembly and a lug pivotally coupled to the casing and having fingers for receiving the stent.

  In yet another aspect, a method for deploying a stent at an implantation site is provided. The method comprises receiving a delivery stem loaded with a radially expandable stent, wherein the delivery system includes a delivery sheath that encloses the stent in a compressed manner over an inner shaft assembly that couples to the stent through a pivotal attachment mechanism. Has a capsule. The compressed stent is delivered through the delivery system through the patient's body lumen to the implantation site. The method also includes retracting the delivery sheath capsule proximally with respect to the stent and pivoting the attachment mechanism to release the stent from the delivery system.

1 is an enlarged view of an exemplary delivery system. FIG. FIG. 7 is a front perspective view of the distal end of a delivery system having an enlarged view of an attachment mechanism configured to connect a stent to a delivery system. FIG. 7 is a rear perspective view of the distal end of the delivery system with an enlarged view of the attachment mechanism configured to connect the stent to the delivery system. FIG. 3 is a cross-sectional view of the distal end of the delivery system. FIG. 6 is a side view of the distal end of the delivery system with the outer sheath retracted. FIG. 6 is a side view of the distal end of the delivery system with the attachment mechanism pivoting lug in a first position. FIG. 6 is a side view of the distal end of the delivery system with the attachment mechanism pivoting lug in a second position.

  The present disclosure generally relates to a delivery system for delivering a stent or stent-graft to a deployment site. As used herein, the term “stent” is intended to encompass both stents and stent-grafts. For example, a stent can have a stent frame, a graft tube coupled to the frame, a prosthetic heart valve coupled to the frame, any combination thereof, and the like. The stent or stent-graft comprises a frame having a normal expansion configuration and a compression configuration for loading into a delivery system. Some embodiments of the frame are a series of wires or wire segments that are arranged to be able to self-transition from a collapsed mode to a normal radially expanded mode or It may be a wire segment. In some structures, the plurality of individual wires that make up the frame support structure are formed of metal or other material. These wires are arranged in such a way that the frame support structure allows folding, compression, or crimping to a compression mode that is smaller in inner diameter than when in the natural expansion mode. In a collapsed manner, such a frame support structure is mounted on a delivery system. The frame support structure is configured to change to a natural expansion when desired, such as by relative movement of one or more sheaths relative to a length of frame.

  The wires of these frame support structures in embodiments of the present disclosure may be formed from a shape memory material such as a nickel titanium alloy (eg, Nitinol ™). With this material, the support structure is capable of self-expanding from a compression mode to a natural expansion mode, such as by application of heat, energy, and the like, or by removal of external forces (eg, compression forces). The frame support structure is also compressed and re-expanded multiple times without damaging the frame structure. Further, the frame support structure of such embodiments can be laser cut from a single piece of material or can be assembled from a number of different components. For these types of frame structures, an example of a delivery system used has a catheter with a retractable sheath that covers the frame until the frame is deployed and at the time of deployment. The sheath is retracted, allowing the frame to self-expand. Further details of such embodiments are discussed below.

  In view of the above, one embodiment of a stent delivery system 30 is shown in FIG. System 30 generally includes a stability layer 32, an inner shaft assembly 34, a delivery sheath assembly 36, and a handle 38. Details regarding the various components are discussed below. Generally, however, the delivery system 30 provides a loaded state in which a stent (not shown) is coupled to the inner shaft assembly 34 and held in a contracted state within the capsule 40 of the delivery sheath assembly 36. . Delivery sheath assembly 36 can be manipulated to pull capsule 40 proximally from the stent by manipulation of handle 38, allowing the stent to self-expand and release from inner shaft assembly 34. . Various features of the components 32-38, reflected in FIG. 1 as described below and described below, can be modified or replaced with different structures and / or mechanisms. As such, the present disclosure is not limited in any way to the stabilizing layer 32, inner shaft assembly 34, delivery sheath assembly 36, handle 38, etc., as shown and described below. More generally, a delivery system according to the present disclosure provides a feature (eg, capsule 40) capable of compressively holding a self-deployable stent and a mechanism capable of releasing or deploying the stent. To do.

  Stabilization layer 32 has a shaft 50, as shown, that is sized to slidably receive over inner shaft assembly 34 and terminates at a distal end 54. (Referenced in its entirety). The shaft 50 can take many forms and generally provide the structural integrity of the system 30 and further allow sufficient flexibility to steer the capsule 40 to a target site (eg, an aortic valve). To. To that end, the shaft 50 is formed of a polymeric material in one embodiment with an associated reinforcing layer. In other embodiments, the stable layer 32 can be omitted.

  The remaining components 34-38 of the delivery system 30 can take a variety of forms suitable for delivering and deploying a self-expanding stent percutaneously. For example, the inner shaft assembly 34 may have a variety of structures suitable for supporting a stent within the capsule 40. In some embodiments, the inner shaft assembly 34 includes a retaining member 100, an intermediate tube 102, and a proximal tube 104. In general, the retention member 100 is similar to a plunger and incorporates features for retaining the stent within the capsule 40 as described below. Tube 102 connects retaining member 100 to proximal tube 104, which in turn couples inner shaft assembly 34 to handle 38. Components 100-104 can be coupled to form a continuous lumen 106 (generally pointed) sized to slidably receive an auxiliary component, such as a guidewire (not shown).

  The holding member 100 includes a tip 110, a support tube 112, and an attachment mechanism 120. Tip 110 forms or constitutes a nose cone having a distally tapered outer surface adapted to facilitate traumatic contact with body tissue. The tip 110 can be fixed or slidable with respect to the support tube 112. The support tube 112 extends proximally from the tip 110 and is configured to support a compressed stent generally disposed thereon from within and has a length and an outer diameter corresponding to the selected dimensional attributes of the stent. ing. Attachment mechanism 120 is attached to support tube 112 (eg, by an adhesive) opposite the tip 110 and is configured to selectively capture corresponding features of the stent. The attachment mechanism 120 can take a variety of forms and is generally disposed along an intermediate portion of the inner shaft assembly 34. In some configurations, the attachment mechanism 120 includes one or more fingers sized to be received within a corresponding aperture formed by the stent frame (eg, the stent frame is an end of the stent frame). A wire loop that is received on each one of the fingers when compressed into the capsule 40). Furthermore, the attachment mechanism 120 includes a pivot mechanism that performs the release of the stent, as will be discussed in more detail below.

  Intermediate tube 102 is formed of a flexible polymeric material (eg, PEEK) and is sized to be slidably received within delivery sheath assembly 36. The proximal tube 104 includes a front end 122 and a rear end 124 in some embodiments. The front end 122 serves as a transition between the intermediate tube 102 and the proximal tube 104, and thus, in some embodiments, a flexible polymer tubing having a diameter slightly smaller than the diameter of the intermediate tube 102 (e.g., PEEK). The rear end 124 has a strong structure configured for robust assembly with a handle 38 such as a metal hypotube at the proximal end 126. Other structures are also envisioned. For example, in other embodiments, intermediate tube 102 and proximal tube 104 are integrally formed as a single homogeneous tube or solid shaft.

  Delivery sheath assembly 36 includes capsule 40 and delivery sheath shaft 130 and defines proximal and distal ends 132, 134. The capsule 40 extends distally from the delivery shaft 130 and, in some embodiments, exhibits sufficient radial or circumferential stiffness to openly resist the expected expansion force of the compressed stent. It has a more stiffened structure (compared to the rigidity of the delivery shaft 130). For example, the delivery sheath shaft 130 may be a polymer tube embedded with a metal braid and the capsule 40 is a laser cut metal tube. Alternatively, the capsule 40 and delivery sheath shaft 130 may have a more uniform structure (eg, a continuous polymer tube). Nevertheless, the capsule 40 is configured to compressively hold the stent to a predetermined diameter when loaded into the capsule 40, and the delivery sheath shaft 130 serves to connect the capsule 40 to the handle 38. The delivery sheath shaft 130 (as well as the capsule 40) is sufficiently flexible to pass through the patient's vasculature and also exhibits sufficient longitudinal rigidity to effect the desired axial movement of the capsule 40. Built in. In other words, the proximal retraction of the delivery sheath shaft 130 is transmitted directly to the capsule 40, causing the corresponding proximal retraction of the capsule 40. In other embodiments, the delivery sheath shaft 130 is further configured to transmit rotational force or motion to the capsule 40.

  The handle 38 generally includes a housing 140 and one or more actuator mechanisms (ie, controls) 142 (shown generally). The housing 140 maintains the actuator mechanism (s) 142 and the handle 38 is configured to facilitate sliding movement of the delivery sheath assembly 36 relative to the inner shaft assembly 34. The housing 140 has any shape or size suitable for convenient handling by the user. In one simplified construction, the first deployment actuator mechanism 142a includes a user interface or actuator (eg, deployment actuator) 144 that is slidably held by the housing 140 and coupled to the delivery sheath connector body 146. . The proximal end 132 of the delivery sheath assembly 36 is connected to the delivery sheath connector body 146. Inner shaft assembly 34, in particular proximal tube 104, is slidably received within a passage 148 (shown generally) of delivery sheath connector body 146 and is rigidly secured to housing 140 at proximal end 126. Combined.

  As noted above, current delivery systems may prevent complete release of the stent because the stent will be caught in the attachment mechanism when the capsule 40 is retracted. In particular, as the stent is delivered, forces (e.g., twisting forces) can cause the stent frame to snag on the fingers of the attachment mechanism 120, thus preventing complete release of the stent. In view of the above, FIGS. 2 and 3 are enlarged isometric views of an attachment mechanism 120 that includes a casing 200, a pivoting lug 202, and an axle 204 to assist in the release of the stent from the delivery system 30. Show. Further, FIG. 4 is a cross-sectional view of the coupling structure assembled in the capsule 40. The casing 200 is directly coupled to the tube 102 with a suitable fastening element 208 (eg, male thread) disposed within the tube 102, and the tube 102 can have an internal thread for receiving the fastening element 208. . The casing 200 further defines a cavity 210 that houses opposing apertures 212, 214 that receive the pivoting lug 202 and the axle 204.

  The lug 202 has an elliptical slot 216 disposed over the support tube 112 and apertures 218, 220 disposed on opposite sides of the slot 216. In addition, the lug 202 includes fingers 222 and 224, and the stent is coupled to the fingers 222, 224 during delivery. In one embodiment, the stent includes tabs or loops that extend from the stent frame disposed within the fingers 222 and 224. Specifically, the fingers 222, 224 are disposed on opposite sides of the lug 202 and form a recessed portion that receives a loop of the stent frame disposed within the fingers 222, 224. When retracted into the capsule 40, the stent frame loop is coupled to the fingers 222,224. Axle 204 has apertures 212, 214 in casing 200 and opposing ends 226, 228 configured to form a press fit or an interference fit, respectively. Further, when assembled, the axle 204 passes through the apertures 218, 220 of the lug 202. The axle 204 also includes a central aperture 230 for the support tube 112 to pass through.

  5-7 show the distal end of the delivery system 30 with the capsule 40 retracted to expose the attachment mechanism 120. FIG. Due to the shape of the slot 216 in the lug 202, the lug 202 pivots relative to the casing 200, for example, to a first position 202 ′ (FIG. 6) or a second position 202 ″ (FIG. 7). Here, the pivoting lug 202 contacts the support tube 112, preventing further rotation of the lug 202 relative to the casing, and the force on the lug 202 by retracting the capsule 40 causes the lug 202 to As a result, the stent 200 is pivoted about the casing 200, and the stent coupled to the casing 200 is released. As a result, the situation where the stent is caught by the attachment mechanism 202 is prevented.

  Although the present disclosure has been described with reference to preferred embodiments, those skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the disclosure.

Claims (6)

A delivery system for deploying a stent percutaneously,
An inner shaft assembly configured to support the stent ;
An attachment mechanism coupled to the inner shaft assembly and configured to selectively engage the stent;
A delivery sheath capsule slidably provided on the inner shaft assembly and configured to receive the stent engaged with the attachment mechanism in a contracted state;
The attachment mechanism is adapted to pivot relative to the inner shaft assembly when the delivery sheath is retracted;
The attachment mechanism is used, the number a casing coupled to said inner shaft assembly, have a finger portion for engaging the stent, and the lug defining a slot, and the axle to couple the casing to said lug, the The lug pivots about the axle and relative to the inner shaft assembly ;
Further, the lug is arranged such that the inner shaft assembly is received in the slot.
A delivery system characterized by that. The lug comprises two fingers configured to engage the stent;
The delivery system according to claim 1. The inner shaft assembly includes a support tube supporting the stent, the support tube being received within the slot ;
The delivery system according to claim 1. The casing includes a fastening element configured to engage the inner shaft assembly.
The delivery system according to claim 1. The casing has a cavity, and the lug is disposed in the cavity.
The delivery system according to claim 1. The lug comprises an elliptical slot adapted to receive a support tube of the delivery system therein;
The delivery system according to claim 1.

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